1. Field of the Invention
This invention relates to a single use syringe for injecting medicine into a patient. More particularly, the invention relates to a safety syringe having a retractable needle cannula that renders the needle cannula harmless after it is used.
2. Background of the Related Art
Many communicable diseases can be spread through the penetration or another having a disease previously used scratching of the skin by a needle that. Spreading of the disease in this manner may occur by accident, such as with medical personnel making injections, or it may occur through misuse, such as by intravenous drug users using a previously used needle cannula.
Various syringes have been invented, designed and developed to retract the needle into the syringe or the plunger inside of the syringe. Some of these devices are U.S. Pat. No. 4,973,316 (Dysarz), U.S. Pat. No. 4,978,343 (Dysarz), U.S. Pat. No. 5,180,369 (Dysarz), U.S. Pat. No. 5,267,961 (Shaw), U.S. Pat. No. 5,019,044 (Tsao), U.S. Pat. No. 5,084,018 (Tsao), U.S. Pat. No. 5,385,551 (Shaw), U.S. Pat. No. 5,389,076 (Shaw), U.S. Pat. No. 5,201,710 (Caselli), and U.S. Pat. No. 6,010,468 (Carter et al). These designs have needles that retract at the end of the injection. Most of these designs have not reached the market due, at least in part, to problems associated with expense of manufacturing, poor reliability or user acceptability. However, even though some of these designs operate poorly and are costly, they have still been commercialised due to the great need in hospitals or clinics for any type of safety syringe.
Most of the existing safety syringe designs allow for automatic retraction of the needle cannula into the plunger barrel of the syringe when the plunger is fully extended into the syringe. The automatic retraction is triggered when the plunger makes physical contact with the distal end of the syringe barrel. Typically, the end of the plunger is provided with a disengageable or sacrificial member at the distal end and the needle cannula is secured by a disengageable or sacrificial member. When the plunger reaches the fully extended position, the physical contact between the plunger and the needle cannula causes activation of the two respective disengageable or sacrificial members. In this manner, the end of the plunger barrel is opened and presented to receive the needle cannula. The needle cannula, no longer secured in position, is biased into the plunger barrel by a spring.
Conventional syringes are typically available in modular systems or kits in which approximately ten different sizes of syringes and approximately ten different sizes of needle cannulas can be used interchangeably. This allows an inventory of twenty items to be used in approximately 100 different combinations in accordance with the present need. However, the safety syringes presently available and described in the above patents are not modular and require stocking of an integral safety syringes for each combination of syringe size and needle cannula size desired, for example 100 different safety syringes. Particularly, in light of the greater cost these syringes, the cost, distribution and storage of safety syringes is much greater than conventional syringes.
Despite the prevalence of modular convention syringes, the emergence of a multitude of safety syringe designs and the increasing public outcry for safety syringes, the complexities of the safety syringe mechanisms have limited the number of attempts to design a safety syringe that is modular. Two such attempts include modular syringe tip designs that are combined with a conventional syringe as described in U.S. Pat. No. 5,891,093 (Dysarz), U.S. Pat. No. 5,935,113 (Dysarz). Compared with the foregoing automatically retracting safety syringes, these two designs can be considered to have safety needle cannula assemblies that are self-contained and manually operated, while being connectable to a conventional syringe and with a conventional locking arrangement. While these devices serve the aforementioned need for modularity, the obvious drawbacks to the devices include the manual retraction mechanism and the additional length that the needle cannula assembly adds to the syringe.
Another design utilises a modified luer-lok that requires pressed fittings, a cutting ring, and a frangible portion that are to be activated or actuated at the same time requiring more hand and finger strength of the user which many medical people do not have. Still another problem with this design is that the needle cannula must be pushed and moved in the direction of the distal end of the needle cannula and if the needle cannula is in an artery or a vein at the time, the needle cannula will pierce the other side of the artery or vein and deposit medication into an undesirable area of the body. Still yet another problem with this design, the plunger tip must enter a restricted area of the luer-lok and restrict and trap the medication still contained in the area of the stopper. And still yet another problem with this design is that when the outer hub is being attached to the luer-lok, the proximal end of the inner hub could be hit by the distal end of the luer-lok fitting and cause the frangible portion to break or otherwise fail.
Each of the foregoing designs has various disadvantages. There are parts that work in a difficult and complicated manner and could be expensive to manufacture. These designs could also be difficult to operate.
The need exists for a safe and disposable syringe that also cannot be reused and still use standard needle cannula of any verity.
It is the object of the present invention to provide a safety syringe module with a safety needle cannula module wherein the safety syringe module reacts with the safety needle cannula module in such a manner that will cause the needle cannula to retreat into the safety syringe module.
Another object of the present invention is to render the needle cannula useless after the needle cannula is retracted into the syringe module to prevent the accidental reuse of a contaminated needle cannula or to further prevent the reuse by users of illicit drugs.
It is still yet another object of the present invention to allow a hospital or clinic etc., to keep a lesser inventory of safety syringes and safety needle cannulas.
The present invention, in at least certain embodiments, provides a syringe with a syringe body with a syringe channel there through, needle cannula apparatus connected to the syringe body with a cannula body and a cannula channel there through, a needle with a needle channel there through and a needle flange at one end, a plunger movably disposed in the syringe channel for pushing fluid in the syringe channel and out through the needle channel, the plunger having a plunger channel there through, a cannula barrier, the needle flange abutting the cannula barrier, the cannula barrier initially preventing the needle cannula from moving into the syringe body, the cannula barrier having a cannula barrier channel there through, a cutter head on the plunger, and a cutter head channel there through, a plunger barrier adjacent the cutter head and initially closing off the plunger interior to fluid, the plunger barrier movable with the cutter head within the syringe body, and the cutter head movable by moving the plunger to break the plunger barrier and the cannula barrier to free the needle cannula so the needle cannula is movable through the cutter head and into the plunger channel. In certain aspects, an optional spring apparatus in the cannula channel urges the needle cannula into the plunger channel upon breaking of the cannula barrier and the plunger barrier.